MainWindow.xaml.cs

using GridTestApp.Models;
using GridTestApp.ViewModels;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;

namespace GridTestApp
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();

            this.DataContext = new MainWindowViewModel();
        }


        private void propertyGrid_ItemMenuRequested(object sender, ActiproSoftware.Windows.Controls.Grids.TreeListBoxItemMenuEventArgs e)
        {
            if (e.Item is CustomPropertyModel model)
            {
                var viewModel = this.DataContext as MainWindowViewModel;
                var target = model.Target as PropertyViewModelBase;

                if (model.Category == "Filter Settings")
                {
                    if (e.Menu == null)
                    {
                        e.Menu = new ContextMenu();
                    }
                    else
                    {
                        e.Menu.Items.Add(new Separator());
                    }

                    e.Menu.Items.Add(new MenuItem()
                    {
                        Header = "Set As Default Settings",
                        Command = viewModel?.CommandSetFilterSettings,
                        CommandParameter = target.DataSource,
                    });
                }
            }
        }
    }
}